The present invention relates to treatment of medical conditions such as tension pneumothorax and particularly to a device for its treatment.
The U.S. military services currently prescribe needle decompression for treatment of tension pneumothorax, a condition which can be fatal if not quickly relieved. The means of treatment for prehospital care should be compact and as simple as practical.
The needle prescribed by the military services is sharp, creating the possibility of damaging underlying organs after initial penetration through the chest wall. It has been reported as well that the needle occasionally plugs with a tissue “core” as it travels through the chest wall. If the plug is detected, the needle could be flushed using a syringe; however it is not certain that the plug would be detected. A 3.15 inch long, 14 gauge angiocatheter needle is used as the standard of care for the U.S. military. Although the catheter is 14 gauge (0.083″ diameter), the inner diameter is 0.058″, and the needle outer and inner diameters are 0.058″ and 0.042″ respectively. This small inner diameter of 0.042″ does not provide an effective means for venting pressurized air quickly from the pleural space. Removal of the needle, leaving the catheter in place, allows better flow, but is not desired, since if it were left in place for long periods it would in essence be an open pneumothorax, and because the catheter is likely to kink and close itself off. The military has considered adopting a 10 gauge needle (outer diameter 0.134″=3.404 mm, inner diameter 0.106″=2.692 mm) to permit greater flow, but it has been found that a larger gauge needle has more propensity to clog with a tissue core.
The Veress needle is a special needle used in laparoscopic surgical procedures. A conventional Veress needle consists of a hollow outer cannula ground obliquely to a sharp point at a distal end, and terminating in a plastic housing at the opposite proximal end. Enclosed within the outer cannula is a hollow tube that has a blunt tip at its distal end (common to the sharp tip of the outer cannula), and that is axially spring-biased in a distal direction by a spring contained in the plastic housing. When no force is applied to the distal end to resist the penetrating point, the spring bias forces the hollow inner tube to protrude just beyond the sharp tip of the outer cannula, obscuring the sharp tip and thereby protecting underlying organs from damage. When a force which overcomes the spring bias is applied to its distal end, as when the Veress needle is being pushed through a patient's abdominal wall, the inner tube is driven back within the outer cannula, exposing the sharp needle tip.
A Veress needle of this conventional configuration may be prone to at least the following shortcomings:                (1) Such a needle may not adequately protect a patient if, when the needle is introduced subcutaneously in the vicinity of vital organs (which is often the case), there is a force of sufficient magnitude to overcome the spring bias of the inner tube and thus expose the outer cannula's sharp tip.        (2) Such a needle may be prone to clogging, as the generally weak spring bias may be insufficient to overcome the resistive forces of tissue or blood which then may become wedged within the hollow outer cannula.        (3) The sharp tip of the Veress needle after use is another potential danger on the battlefield and is a challenge for the military.        
Kulkashi (U.S. Pat. No. 5,098,388) discloses a Veress needle containing a mounted fluid transfer means such as a bobbin that moves out from the proximal end of a distal handle of the device when the needle is penetrating tissue, and that retracts into the handle when the needle has passed through the tissue and the inner tube moves in a distal direction to expose its distal end beyond the sharpened end of the hollow needle. The bobbin portion can be manually moved for repetitively retracting and extending the inner tube, in a manner causing the gas exit hole to wipe against an edge of the needle point, theoretically clearing the gas exit hole in the distal end of the inner tube.